free:

I've long wanted to be able to link directly to my library's and also Library of Congress records, but the URLs generated in Voyager Endeavor (now ExLibris Voyager) are, alas, unstable. However, some enterprising enterprisers developed this canned search generator that creates a stable URL for your search or for the record itself in multiple views.

The Library of Congress, thanks to Muppet Wiki, welcomes MISS PIGGY, also BEARS AS PETS (not referring to Fozzie Bear, thank you very much), and what seem to be inconsistent headings for people who lived in countries before Europeans found them.